Electric heating unit



April 6 1926. 1,579,732

F. E. OWEN ELECTRIC HEATING UNIT Filed August 2. 1924 Frederick E. Owe/7.

ATTORNEY devices and Patented Apr. 6,

FBE'DERIcx E. oWEN, or viiesr rALEsTINEfoHm;

ELECTRIC HEATING UNIT.

d application 'mea August 2,1924. seria; No. 729,677.

To all whom t may concern: Be it known that I, FREDERICK of East Palestine, inthe county of Columbiana and State of Ohio, have invented a new and useful Improvement in Electric Heating Units, of which the following is a specification.

Another object of my'invention is to provide a semi-encased lheating unit in which the cooler portions of a refractory member, comprising a part of the unit, shall beencased in metal to prevent absorption of odors. v

Another object of my invention is to provide a heating unit embodying a resistor- 5 therefor with interfitting means for 'preventing relative movement of the two parts. In practicing my invention I provide a plate of refractory electric-insulating material having a substantiallyopen groove in inits upper f ace. I rovide further a metal casing, of substantial y cup-shape', that'surrounds the bottom and the side portions Aof the plate, and is bent aroundor over anv upper shoulder of therefractory plate.' The casing is providedwith a lurality of lugs to receive the inner end o metal housings within which are located terminal member assemblies suitably insulatedtherefrom, and held.I therein by a metal cap member having screw-threaded engagement with the housme. 1 l

In the single sheet of. drawings,

Figure 1 is a top plan View' of ,a heating unit embodying'my invention, certain iportions thereof being cut awayA to showthe interior construction thereof.-

Fig. 2 is Va view, 1n vertical sectiontherethrou'h a. rtion onl of the unit -being gr 1 l g p0 y A metal casing 17, of substantially -c'upl vshown on antenlarged scale, and, l

Fig. Bfs a fragmentarv view, m

struction embodying m invention.

A brick or platell, o refractory ,electrlc- OWEN, a citizen of the United' States, and a resident 'metrally-jspaced positions. vIf

vertici section showing a modi edl formof con-v rality jof spiral grooves 12 and .13 inl-its upper surface. The plate l11 may be of any #UNI-'nsoAv STATES IPA'llll-l,"v 'OQFFlM-CE? suitable o-r desiredv contour anddimensions as may be requiredbythe device or apparatus with which it is to be operatively asso# ciated and which itis to heat. Hence while I' have villustrated .a substantially circular plate, I 4do not desire to rbe limited thereto, as the plate may be square or rectangular.

-A`resistor member 14 that may compriseA a suitable metal wire wound into extended helicalform is located in the l substantially t open grooves 12 and 13. 'Any suitable or desired means for holding or retaining the resistor 'member 14.- in the otherwise open groove or grooves may be provid ad,butA I have illustrated av preferred Iconstruction that is more particularly H described 'and f claimed in a co-pending application by Clarence W. Williams, Serial No. 689,467, filedl J an. 30, .1924.

The 4means for retaining the resistor member -within the grooves comprises a plu- 15 thatl are integral .withone of the'si e supporting member and a metal casingirality of spaced horizontally-extending lu s soi..

of the groove,lboth ribsbeing spaced-from the integral lug. `A`s ismore particularly explained in the hereinbefore;"mentioned application, the helicallywoun'd l resistor member is placed inits proper 'operative po-` sition by a movement thereof at substantially right anglesv tothe, face of 'the refractory plate, after which'r it `is Ipressed into .the groove and held. below the over-hanging .lugs `rby the opposing spaced ribs'. l

I have illustrated a palr of spiral groovesv in order that one end of the resistor member',

may be located in Vfsubstantially dia'metrally-` spaced position relatively to the'other end f-v thereof `and that suitable terminal members connected thereto may 4beulocatedfin dini contour of refractory plate and heating unit a, differentiv l.

is employed al different configuration of oove or `grooves maybe used;

shape, is providedfor the refractory plate 1 1,v and is of substantially the saine contour plate "I1/1.# The platel 11 fitsfsnuglywit-hin t The plate 11 is provided, at. its upper por- Ation and adjacent to the edge thereof, with a shoulder portion 19 having a shallow groove 21 therein to receive a resilient gasket member 22, that may also be of asbestos. The upper edge portion of the annular part of the casing 17 is bent overthe shoulder ingt portion 19 and into closevenga ement with the gasket 22, whereby substantlally all but the upper grooved surface of the plate 11 vis covered by a metal casing.

The metal casing 17 is provided with `a pair of integral hollow lugs 24 that extend a short distance radially from the periphery of the casing 17 and have their inner surface provided with suitable screw threads 25. A metal housing 26, that may be of substantial- -ly circular form in lateral section, has an inner reduced end portion 27 that is provided with external screw threads adapted to engage the screw threads 25 on the lug 24. The housing 26 is of substantially tubular form, the inner diameter of the portion 27 bein suiiiciently large to permit otextendierethrough the reduced inner end portion of a tubular member 28 of a refractory electric-insulating material. A metal terminal pin 29 has aportin extending through the member 28 and has also an outer end portionextending outside of the housing 26, an intermediate integral flange portion 31 being provided thereon of greater diameter than the other parts of the terminal pin. A washer 32,' ofl fibrous, resilient, electric-insulating material such as asbestos, is located A between the outer end of the portion 27 of the vhousing andthe inner face of the outer enlarged end portion of the member 28. A substantially similar Vwasher 33 is located A. between the outer end surface of the member '28 and thefinner Ysurface of, the enlarged ortion 31. An annular collar 34, also of brous electric-insulating material, is provided between the outer periphery of the portlon 31 and the inner surface of the'hous- 111g 26.. A .bushing 35, that is preferably also of a. fibrous and resilient material'such as asbestos, surrounds the outer, portion of the terminal pm 29 and has its lnner surface in operative engagement with the outer surface of the enlarged portion 31. A metal -cap member 36,l of substantially cup-shape,

tits over a portion of the bushing 35 and has screw-threaded engagement with the outer end of the housing 26.

The inner ends of the members 29 extend into chambers 37 that are provided in the refractory plate 11 at substantially the bottom portlon thereof. The inner ends of the and are provided with screw threads. A'

washer member 38 is pressed against the inner .end of the refractory insulating bushing 28 by a nut 39, and one of the ends of the resistor member 14 is clamped around the end of the'terminal pin 29 and against the nut 39 by a second nut 41.

' I n Fig. 3 of the drawing, l'have illustrated a modied form of terminal member aggregate, the main dierence from that illustrated in Fig. 2 of the drawing being in the method of connecting the end of thc resistor member to the-terminal pin 29. The terminal pin '29 is made longer in this form and is provided with a screw-threaded opening 42 extending laterally,therethrough at the inner end thereof, which end may be provided with flattened portions as illustrated by the numeral 43 in the drawing. A machine screw 44 extends from the bottom of the outer end of the groove through an opening 45 into the chamber 37 'and is adapted to iit into the screw-threaded opening 42.

trical connection is made between the resistor member 14 and the terminal pin 29.

In the assembly of the heating unit the resistor member 14 may be placed in the open groove andthe refractory plate may then be placed within the casing 17 and the upper flangev portion 23 may be turned over on the gasket 22 and the shoulder 19 by any suitable means, such as by rolling or by a suitable press. The ends of the resistor member 14. are brought out through the respective chambers 37 and through the lugs 24and also through the housing 26 which latter have been Screwed into the co-operating lugs. The terminal pin 29, in the construction illustrated in Fig. 2 of the drawings, is mounted in its proper operative position relatively to the insulating bushing 28 and the insulating washer 33, the metal washer 38 andthe nut 39 being located thereon. The end of the resistor member 41 is placed around the reduced inner end portion of the pin 29 and held there by the nut 41 which is drawn up tight.

The above described connection of the end of the resistor wire 14 to the ends of the terminal pins is made with the inner end of the terminal pins located just outside of the outer ends of the respective housings 26, after which the terminal pin and the insulating Imembers operatively associated therewith are pushed into the housing and into substantially the position illustrated in Fig. 2 of the drawing. The initially extended ends of the resistor wire will thereby be caused to coil up in the chambers 37. The

insulating collar 34 is then put into place llO are to be located thereabove.

member 36 may be mounted on the housing, whereby the terminal pin assembly is held in its proper operative position within the housing and in substantially the position illustrated inl Fig. 2 of the drawing.

`IVhen the modification illustrated in Fig. 3 of the drawing is employed, the terminal pin, together with the refractory bushing 28,

`and the inner washers 32 and 33, are pushed into the housing and into substantially the position illustrated in this figure of the drawings. The screw 44 may then be placed in its proper operative posltion in the opening 45 and be causedv to engage the inner end of thev terminal pin. AAfter this the annular member 34, the bushing 35, and the cap member 36 may bemounted in their proper operative positions, substantially as illustratedin the drawings, thereby to hold the terminal pin in its proper operative position withm the housing.

A heating unit ofthe herein described construction is particularly applicable for use in electricallyheated cooking devices of the fireless cooker type, wherein the heating unit-is to be located at the bottom of the cooking chamber and the cooking vessels A refractory plate is very desirable to support the otherwise open or bare heating element or resistor member because of'its relatively high elecj tric-insulating characteristics. It has, howwardly from the refractory` ever, the drawback of being relatively porous, and will tend to absorb odors from the food being cooked. By providing a substantially bare heating resistor II amenabled to raise the temperature of the cooking vessel very quickly, particularly lif the cooking vessel is permitted to rest directly upon the top, surface of'the refractory plate. The metal casing surrounds and covers all of the surface of the refractory plate that is not occupied by the heating element, and prevents the absorption of odors from the food being cooked by those parts of the refractory plate that are at somewhat lower temperature thanthef resistor member itself or those parts of the refractory plate closely adjacent to the resistor member.

The metal casing may be made either in -the form of a punching or it may be made a casting. The plate 18 of heat-insulating material located between the bottom'of the refractory plate and the bottom of the casing tends to reduce the ow of heat downplate.

Any suitable or desire construction of stationary contact members may be provided in the cooking device with which a heater unit embodying my invention is to be associated, and this contact menber may be of aj resilient type to permit of easy and quick insertiomtherein and removal therefrom of the projecting terminal pins.` v

The thickness of the insulating bushings 35 may be made as large as is found suitable or necessary in view of the fact that the creeping-distance between the terninal pin and the metal cap member must be large enough to prevent a ground developing Ytherebetween when the heating unit is used in a substantially closed heating chamber that may be filled with moisture-laden vapor from the food being cooked.

It may be noted further that it is intended to operate the resistor member 14 at such a relatively high temperature that no cooking odors will be absorbed by the refractory material located immediately adjacent thereto. In case any of the food should be spilled on the upper surface, as by boiling over, the relatively high temperature of the heating element and of the upper surface of the heating unit will burn any such food and in this Way also tend to prevent the cooking odorsv from being absorbed by4 the refractory plate.

A heating unit embodying my invention may be easily and quickly repaired in case of a burnout of the resistor member, as the latter may be quickly removed, as may also the cap members from-the terminal member assembly, to permit of disconnecting the ends of the resistor wire from the terminal pins. Re-assembly may be effected as was hereinbefore described.

As the terminal pins extend into the chambers in the refractory plate, to interit therewith, relative movement of the casing and the refractory plate is effectively prevented.

l/Vhile I have illustrated my invention in a preferred embodiment, I do not desire to be limited to the exact structures shown in the drawing, and desire that only such limitations shall be placed upon the claims as are imposed by the. prior art.

I claim as my invention y 1. In a heating unit, in combination, a refractory member having a substantially open groove in `one. face thereof, a resistor member in said groove, and a metal casing of said refractory member periphery onl and secured t ereto. 2. In a heating unit, the combination with a refractory ymember of electric-insulating material having a substantially open groove vinone face thereof, and a resistor member ,enclosing the bottom 'surface and the annular ber and having the rim thereof bent over said refractory member below the upper surface thereof.

4. In a heating unit, the combination with a refractory member of electric-insulating material having a substantially open groove in one face thereof, and a resistor member in said groove, of a metal casing, of substantially cup-shape, enclosing the bottom and the sides only of said refractory mem, ber, and a terminal member aggregate supported by said meta-l casing and interitting with said refractory member.

5. In a heating unit, the combination With a refractory-member of electric-insulating material having a substantially open groove in one face thereof, and a resistor member in said groove, of a metal casing, of vsubstantially cup-shape, enclosing the bottom and the sides -only of said refractory mem- .'ber, a terminal housingsupported by said casing, a'terminal pin insulatedly mounted in said housing and interfitting with said refractory member, and a cap member on said housing for holding said terminal pin therein.

' 6. In a heating unit, the combination with a refractory member of electric-insulating material, and a resistor member located in one face thereof, of a metal casing member, of substantially lcupshape, for receivng said refractorymember, and integral means on said casing member for holding said re` fractory member therein.

7. In a heating unit, the combination Withv a refractory member of electric-insulating material, and a resistor member located in one face thereof, of a meta-l casing member, of substantially cup-shape, enclosing said refractory member on all surfaces except member-to prevent relative movementsgof the two members. y i

9. In a heating unit, the combination with a refractory resistor-supporting member,

member and projecting into said refractory and an enclosing casing therefor, of vmeans supported by said casi-ng for preventing relativev movement of said refractory member and said casing.

l0. In a heating unit, the combination` with a refractory member, a resistor supported thereby, and an enclosing casing,

of means vconstituting terminal members for said resistor and effective to prevent relative movements of said refractory member and said casing.-

-l1. In a. heating unit, the combination With a refractory member, a substantially uncovered resistor member locatedin the upper surface thereof, andy a metal casing enclosing all of said refractoryv member,

except the upper surface, of a plurality of and interfitting with said refractory` member -to prevent relative movement thereof'. In testimony whereof, I have hereunto terminal members supported by said casing subscribed my name this 31st day of July,

FREDERICK E. GIVEN.y 

